The idea that a private 'army' of deserters, drawn from every nationality fought in the Peninsular War, may stretch credulity too far. Not as far, perhaps, as the idea of a 'Rocket Troop'. Yet both existed.
Pot-au-Feu lived, a renegade French Sergeant who promoted himself to Marshal, and who survived by terrorising a wide patch of Spanish countryside. His followers included French, British, Spanish and Portuguese soldiers, and his crimes included kidnapping, rape, and murder. I fear I have made him into a man pleasanter than he really was. The French General de Marbot tells how the French destroyed him and then handed the allied deserters over to Wellington's forces. Sharpe, I fear, has taken credit for a French success.
In another distortion of history I have brought the Rocket Troop to Spain a few months early. Wellington first saw a demonstration of Sir William Congreve's Rocket System in 1810 when a Naval detachment brought some weapons ashore in Portugal. Wellington was unimpressed. By 1813, however, a Rocket Troop had joined his army and it enjoyed the enthusiastic patronage of the Prince Regent. In its workings I have stayed close to the Instruction Book written by Sir William Congreve himself (even down to the detachable lance-heads, surely a triumph of inventor's hope over judgment). It was an extraordinary system that had, at its most ambitious, a 'Light-Ball' rocket that delivered a parachute flare for night fighting. And this in 1813! The Rocket Corps itself came into formal existence on January 1st, 1814, though it had already been deployed in the Peninsula and, indeed, Congreve's system had been sold in 1808 to the Austrian army where it was known as the Feuerwerkscorps. Wellington continued to mistrust it, though he used it at the crossing of the Adour, while in Northern Europe, it had its most successful day at the Battle of Leipzig where foreign observers were much impressed. A rocket battery was present at Waterloo and in some pictures of that engagement the rocket trails can be seen over the battlefield.
Though it was never a great success, the Rocket Corps has enshrined itself in history thanks to one of the enemies against whom it was so ineffectively employed (the problem was simply accuracy, which is why Sharpe chose to wait until they could hardly avoid hitting the enemy). Rockets were deployed in the war of 1812 against the United States, used by the British in their siege of Fort McHenry. A song was written about that siege and then put to the music of a drinking song used by the Anacreon Club in London. Those words and that tune now comprise, of course, the American National Anthem. It is strange to think that whenever 'The Star-Spangled Banner' is sung, before every baseball and football game, Britain's erstwhile enemies recall Sir William Congreve's invention in the line 'the rockets' red glare'. Thus did Britain's secret weapon find lasting fame!
Sir Augustus Farthingdale plagiarized his book mainly from Major Chamberlin's book, and now I must confess to a plagiarism. Sharpe's Christmas meal, and the hare stew that Pot-au-Feu ate in the Convent, all came from Elizabeth David's magnificent French Provincial Cooking, a book that has given me more pleasure than most. If any reader would like to recreate Sharpe's Christmas meal (a rewarding experience!) then I refer to them to Mrs David's magnificent work. Potage de marron Dauphinois (Chestnut soup), Perdreau Roti au Four (Roast Partridge), and the Cassoulet de Toulouse a la Menagere, to which I added roast potatoes for Sharpe's sake, and changed the recipe to fit the foods which might have been available in winter Spain. The hare stew exalts in the name Le Civet de Lievre de Diane de Chateaumorand. Strictly speaking it is not a stew, but I will not attempt the impossible and try to rival Elizabeth David as a cookery writer. My thanks to her.
Beyond the army of deserters and the rocket system, all else in Sharpe's Enemy is fiction. There is no Gateway of God, nor was any battle fought over the Christmas of 1812. The 60th existed, the Royal American Rifles, but all other Regiments are fictitious. I wanted to write one story that reflected the last winter when the British would be pinned back again in Portugal. Despite Napoleon's crushing defeat in Russia it must still have seemed to many soldiers that the war could last forever, yet within months Wellington's strategy changed the whole Peninsular War and never again were the British to retreat. Sharpe and Harper will march again.